lessons appearing blank

Trying to set up lessons in courses for students. The lessons appear when I edit, but when I publish lessons appear blank.

I tried changing premalink from the default, still just blank. Running 2017 theme and tried in 2020 and the same. Any help appreciated.

I checked to see if others had similar and most issues seem to be around permalink and themes. Not sure what to check next.

The page I need help with: [log in to see the link]